tRNA methylating enzymes isolated from E. coli 113-3 grown in a medium with methionine or S-methylmethionine differed in the activity of transfer of the 14CH3-group from 14CH3-S-adenosyl-L-methionine (SAM) to tRNA in the in vitro experiments in heterological systems consisting of tRNA methyltransferases from E. coli 113-3 and a substrate of methylation, viz. methyl-deficient tRNA isolated from E. coli K 12W6. In such a system, tRNA methyltransferases from E. coli 113-3 grown on S-methylmethionine methylated tRNA from E. coli K 12W6 at a rate almost twice as high as that in the case of the culture grown on methionine. At the same time, the activity of guanine methylation yielding 7-methylguanine increased significantly. The protein obtained after precipitation of cell-free extracts with ammonium sulfate was separated into four fractions using a system of columns packed with Sephadex G-25 and DEAE-cellulose. These fractions differed quantitatively in culture grown either on methionine or S-methylmethionine.

The biosynthesis of exoproteases by Actinomyces spheroides 35 was studied in the conditions of limitation of the growth medium with the source of carbon, nitrogen and sulfur. The absence of these sources from the medium was found to induce the synthesis of exoproteases by the washed mycelium of Actinomyces spheroides. The enzymes were synthesized at a highest rate in the absence of nitrogen and sulfur sources. Protein as a sole source of carbon, nitrogen or sulfur in the medium suppressed rather than induced the biosynthesis of exoproteases by the culture.

The effect of various factors on the activity and biosynthesis of nitrogenase in Clostridium butyricum was estimated by the rate of acetylene reduction at different growth phases in the static culture. The activity of nitrogenase was found to be low in vegetative cells; it increased and reached the maximum at the stage of prospore formation and decreased in the course of sporulation. The duration of different stages in the cell growth cycle depended on temperature and the composition of the medium. An increase in the rate of nitrogenase synthesis at the stage of prospore formation was favoured by the presence of sodium acetate or yeast autolysate in the medium; ammonium chloride inhibited the mechanism of nitrogenase biosynthesis. Cytoplasmic membranous structures such as tubular-vesicular or lamellar mesosomes were formed in active nitrogen fixing cells grown in a medium with yeast autolysat. Such structures were absent from cells with a low activity grown in a medium containing ammonium chloride.

The role of systems for glucose transport in the manifestation of carbon catabolite repression of glucoamylase synthesis was studied in the yeast Endomycopsis fibuligera. Experimentas were conducted with its mutant AB-192 defective in the system of transport universal for glucose and 2-deoxy-D-glucose (2-DG). The nature of the mutation was established from the following data: (1) transport of labeled glucose into the mutant cells was twice as low in comparison with the parent culture 20-9; (2) transport of labeled 2-DG was suppressed almost entirely; (3) no competition was found between glucose and 2-DG for penetration into the mutant cells. Glucoamylase synthesis in the mutant AB-192 was not sensitive to catabolite repression by glucose. This was confirmed by the resistance of the AB-192 cells to the inhibition by glucose and their complete resistance to the repression by 2-DG. Moreover, an addition of cAMP did not stimulate glucoamylase synthesis by the mutant culture in the presence of glucose and 2-DG. It can be concluded therefore that the resistance of the yeast to catabolite repression by the glucose is caused by the mutation in the system for carbohydrate transport. The results suggest that the system of glucose transport plays an important role in the manifestation of carbon catabolite repression in the yeast Endomycopsis fibuligera.

The purpose of this work was to study the action of acridine orange and mitomycin C on the production of mutants of Streptomyces hygroscopicus, strain 0681. The mutagen activity of mitomycin C was shown to be high. The vegetative culture grown for 24 hours produced more mutants under the action of mitomycin C than spores did. Both acridine orange and mitomycin C caused the production of mutants in strain 0681. The morphology of colonies in these mutants was modified, the synthesis of hygromycin B was completely or partly blocked, and the composition of fatty acids changed quantitatively and qualitatively. Mutants induced by mitomycin C were highly active in the production of the complex of hygrolytin proteolytic enzymes.

The effect of detergents, i. e. cationic, anionic, nonionic and polyelectrolytes of the cationic type on the efficacy of chloramphenicol against resistant strains of E. coli and Staph. aureus was studied. It was found that the detergent effect on inactivation of chloramphenicol by the bacterial resistant strains was inconsistent. The cationic detergents and in particular chlorhexidine had the most pronounced inhibitory effect. In subbacteriostatic concentrations they significantly suppressed inactivation of chloramphenicol in the cells of E. coli and Staph. aureus. The anionic detergents and polyelectrolytes of the cationic type in the above concentrations were effective only with respect to Staph. aureus. It is noted that the detergents increased the activity of chloramphenicol against E. coli and Staph. aureus.

The effect of o-aminoazotoluene (OAT) on the activity of tyrosine aminotransferase (TAT) from mouse liver cytosol under its incubation in the presence of the systems providing for the metabolic activation of the cancerogen (liver microsomes and NADPH2) and dephosphorylation of TAT molecules (light mitochondria and ATP) was studied. It was shown that OAT has neither direct nor indirect (via the phsophorylation--dephosphorylation systems) effect on the activity of TAT. It was concluded that the decrease of TAT induction by hydrocortisone in vivo resulting from injection of OAT to the mice is not due to the direct influence of the cancerogen on the enzyme molecules.

Estrogen-dependent mammary gland tumors, induced in rats by DMBA, were found to show a high content of estradiol receptors. Among hormone-dependent tumors there were ones both with low and high content of the receptors. Loss of estrogen dependence by tumors with a high level of estradiol receptors is due to an impairment of the translocation of estradiol-receptor complexes into nuclei. Only in estrogen-dependent tumors the activity of hexokinase, pyruvate kinase and glucoso-6-phosphatedehydrogenase was changed following ovariectomy and administration of estradiol to the animals.

Content of components and functional activity of monooxygenase enzyme system were studied in rat liver tissue during hepatocarcinogenesis produced by diethyl nitrosamine treatment. Content of cytochromes P-450 and b5, NADPH- NADH-cytochrome c reductase and demethylase activities as well as capacity to induce the monooxygenase enzyme system after administration of its inductors were not altered in chronic treatment with carcinogenic doses of diethyl nitrosamine. The higher doses of the amine were shown to reduce the content of the cytochromes in liver tissue.

The lethal and mutagenic effect of mitomycin C in doses of 10 and 15 micrograms/ml on the spores and 24-hour culture of Act. hygroscopicus, strain O878 producing hygrolytin, a proteolytic enzyme and hygromycin B, an antibiotic was studied. It was found that mitomycin C had a high lethal effect on the organism. The lethal effect of the antibiotic depended on the stage of the culture development, mitomycin C dose and exposure time. The 24-hour culture was most sensitive to the effect of mitomycin in a dose of 50 micrograms/ml. Exposure to mitomycin increased the actinomycete variation with respect to the colony morphology and induction of new morphological mutations. Exposure of strain O878 to mitomycin C significantly increased the culture variation with respect to the quantitative features of production of the hygrolytin proteolytic enzyme complex and hygromycin B. The character of the strain induced variation with respect to the features studied was different which indicated the absence of correlation between them. The use of mitomycin C proved to be promising in selection of Act. hygroscopicus with a purpose of increasing the culture proteolytic and antibiotic activity.

A comparative study of the ability of phenobarbital, testosterone and their combination to induce the liver microsomal monooxygenase system after 9-day administration of these compounds to intact male and female rats was carried out. It was shown that administration of testosterone does not increase the level of cytochromes P450 and b5 in the livers of male and female rats. However, after a combined administration of the two compounds testosterone significantly enhances the inducing effects of phenobarbital (i. e. superinduction) in female rats; no such effect was observed in the livers of male rats. The rates of oxidation of hexobarbital, ethylmorphine and testosterone by liver microsomes are also increased after a combined administration of the two inducers. However, the additive effects of the two substances on substrate oxidation are observed when the latter was calculated per mole of cytochrome P450. An administration of testosterone to male rats does not result in an increase of the rate of hexobarbital and testosterone oxidation by isolated liver microsomes.

Restoration of tyrosinamine transferase (TAT) with cortisol in the rat hepatocytes after the cessation of prolonged (for many days) administration of this hormone was investigated. The effect of the liver regeneration and insulin administration on this process was also studied. In single cortisol administration the TAT activity rose 5-fold; the induction response decreased after 21 days of daily administration. The TAT induction in response to cortisol administration was restored completely only on the 25th--30th day after the cessation of this hormone injection. A three-day insulin administration led to the restoration of TAT induction in response to cortisol administration. The process of the liver regeneration during the first 24 hours after partial hepatectomy induced TAT in the cells of both control animals and those given cortisol for prolonged periods; besides, it aided restoration of the induction response to cortisol administration.

Oospora lactis was found to use Tweens 20, 40, 60 and 80 as a source of carbon in a nutrient medium for lipase biosynthesis. The highest production of lipase was registered in the medium with Tween-80. The lipase activity of the culture increased if even small quantities of Tweens 40, 60 and, particularly, 80 (0.05--1.0%) were added to the medium containing cottonseed oil. All the tested Tweens stimulating the biosynthesis of lipase were also, at a particular concentration, the inhibitors of this enzyme.